Stripe Rust Update 3/25/03

March 25, 2003

Xianming Chen

Wheat stripe rust is developing in Texas, Louisiana, California, and western Washington. In Texas, severe stripe rust epidemic is widespread. The major cultivars, especially ‘Coronado’ that is grown about 80-90% of the 350,000 acres in six counties in central Texas, are highly susceptible. ‘Jagger’ and a new variety ‘Cutter’ are the only hard red wheat varieties that are resistant in the region. This year, stripe rust is much more severe and widespread than that in 2001, another year of most severe epidemic. Growers have been spraying wheat fields with fungicides. In Louisiana, stripe rust started showing up in mid March. Some fields were sprayed with fungicides. In California, stripe rust was reported on wheat on February 20 and barley on February 27, which were the earliest observations of stripe rust in a number of years. Wheat stripe rust is increasing on susceptible varieties in nurseries and commercial fields in the Sacramento Valley and is severe on early planted forage wheat (Dirkwin) in the northern San Joaquin Valley. Stripe rust is occurring throughout the San Joaquin Valley.

In Washington State, stripe rust was severe (about 30-50%) on susceptible varieties in the wheat nurseries near MT Vernon last week. Light stripe rust was found in some commercial wheat fields in the Skagit County. Stripe rust of barley was found on susceptible varieties in the barley nurseries. The stripe rust situation in northwestern Washington is normal.

The group of races, especially PST-78, were predominant throughout of the United States last year and are occurring this year. Susceptible cultivars like ‘Zak’ will be vulnerable to stripe rust this year. Because the past winter was mild, which was favorable to stripe rust survival, we predict that stripe rust may occur early this year. For spring crops, growers should plant resistant varieties such as ‘Alpowa’. More acreage of resistant cultivars should reduce the possibility of widespread epidemic. If susceptible winter wheat varieties have been planted and susceptible spring wheat varieties are going to be planted, be prepared for fungicide application.

If you have any questions about stripe rust, please contact Xianming Chen (509-335-8086, xianming@mail.wsu.edu) or David Wood (509-335-4789, dawood@mail.wsu.edu).